With this in mind we have produced a short, practical guide for growers which highlights some of the most important areas where action needs to be taken.

Admit you have a problem

The first step towards beating blackgrass is admitting there is a problem – after all 12 blackgrass plants/sq m can shrink yields by about 5%, with densities of 100 plants/sq m having the potential to cut yields by 2t/ha. Growers need to be more prepared to confront the issue of failing post-emergence control and be proactive in changing their tactics. Too many people hope the season will be in their favour, or optimistically expect control to be better in the following crop. If you are spending over £100/ha on herbicides in wheat there is probably a problem that needs to be addressed.

Have a farm policy

Everyone who works on the farm needs to know what they are aiming for – so decide what your farm policy is towards blackgrass and then share it with the whole team. That includes the farm owner, family members, manager, workers, contractors and agronomist. They need to know whether you are looking for zero tolerance or containment to an acceptable level year-on-year. A field-by-field flexible strategy may be necessary. It’s all about attitude and a joined up approach in the first instance is better than the historic approach of a grower making the decision and leaving the agronomist to find a solution from a can.

Sustainable rotations

For farms needing to beat blackgrass and following a wheat – wheat – oilseed rape rotation, Strutt & Parker now recommend a new five course rotation with a double spring break. This is winter wheat – spring barley – spring beans – winter wheat – oilseed rape. Typically, a first winter wheat after a pulse suits a Group 1 milling wheat and this enables OSR to follow a wheat instead of spring barley, making good use of the earlier harvest window for improved OSR establishment. Use the plough one year in four or five as a ‘reset’ button to maximise annual seed decline and avoid slackening herbicide inputs on the break crops. The most successful farms keep a steady consistent rotation and employ the plough.

Consider OSR carefully

Earlier drilling for flea beetle means OSR is put under high pressure for control. So do not grow OSR where a high seed return has occurred. Consider low disturbance drilling to aid the efficacy of October/November applied residual herbicides (propyzamide and carbetamide). Ensure failed patches, corners and tramlines are sprayed out to stop seed return.

Variety choice

A 2-3% yield difference between varieties on the AHDB recommended list is insignificant compared to losses from poor blackgrass control. Select varieties that are vigorous and will suit a later sowing slot and will establish to growth stage 30 rapidly. Skyfall, Siskin, Basset are good examples of the newer varieties.

Sequence your autumn drilling

The most important factor in determining control with pre-or post-emergence residual sprays is access to moisture, so getting the benefits of autumn rainfall is critical. An earlier-drilled crop, treated with a well-timed pre-emergence application when there is moisture available, will be better than a later drilled crop with a pre-emergence application which remains dry. However, on the worst-affected fields, delay drilling until after 20 October to give yourself the best chance of control and time applications to coincide with available moisture from rainfall. Ideally, rainfall is required within a week of the pre-emergence application to maximise efficacy and keep control levels where they must be.

Drilling rates

In wheat, 400 seeds/m2 sown may be required to aid competitiveness of the crop, but bear in mind the seed bed quality in late October could result in percentage establishment well below 50%. Switching to a tine drill from a disc coulter is also likely to reduce percentage establishment. In spring beans, a 20% increase in established plants is necessary to compete with germinating blackgrass in between rows.

Upscale labour and machinery costs

Many growers have moved to spring cropping and delayed drilling in order to get more consistent pre-emergence control, but this shortens the working window which can mean an extra man and additional drilling capacity is required. This could take the form of a wider drill, a low disturbance drill or an additional mounted tine drill for conditions where a disc coulter will not work. However, remember that if herbicide costs are currently in excess of £150/ha, this could be reduced by later drilling with the saving capitalised into the extra drilling capacity.

Eliminate seed return

Preventing seed return is the most important part of reducing blackgrass populations. If the post-emergence control is not satisfactory, make a decision pre-Christmas and plan a spring crop. Where infestations are worst, consider the use of glyphosate or whole crop but timing will be critical. Whole-crop silage needs to be made before there is a danger of knocking the viable seed to the ground (May) and spray needs to be applied once the blackgrass has come into head. Eliminating seed return seems to buy two to three years of good control in the following crop and is the justification for such drastic action.

Machine hygiene

To avoid spreading a blackgrass problem by machinery, sequence the cutting of fields to clear clean fields first. Consider leaving infested headlands to last and cut the middle of the field first. Leaving straw in the swath and baling can also help reduce spreading across the field.

It is also important to blow down the combine after cutting any infected field and before moving blocks or farms. Contractors should be just as vigilant about the cleanliness of their machinery. Finally, only bring muck and straw onto the holding from trusted sources.

Chemical awareness

Good blackgrass control can be compromised by minor changes in the timing and accuracy of application. Raise the bar of training on farm regarding the timing of pre-emergence sprays, nozzles, boom height, forward speed and the need to back into corners and around poles. Consider whether you could train an employee to BASIS standards, so they can make decisions on farm instead of waiting for the agronomist to visit. Forward speed needs to be slow enough to prevent a vortex behind the boom (10-12kmph) and follow the manufacturer’s guidance on boom height for the specific nozzle (typically 50-80cm).

Land drainage

Uncompetitive crops associated with poorly drained land is a common source of blackgrass seed return. There is no excuse for poor maintenance of ditches, outfalls and rotational mole ploughing where appropriate. On owner-occupied land, a new drainage scheme or strategic installation of drains in problematic areas should be installed to give effective drainage and improved grass weed control.

Plan for the long term

The on-farm costs of resistant blackgrass are too high to ignore. Analysis of spending on large, heavy-land farms showed the total herbicide costs of controlling blackgrass in wheat and rape rose between 2006 and 2015 – from £65/ha to £134/ha in the wheat and £72/ha to £103/ha in the rape. There were also other financial implications from having to change the rotation. For farmers looking to expand, land coming up in the next few years is likely to come with high blackgrass pressure and those with a winning blackgrass control strategy are likely to be those who are successful when tendering for a Farm Business Tenancy or Contract Farming Agreements